9+3+1/3 sampai 10 suku

jawab

deret geo
a= 9
r= 3: 9 = 1/3

s10= a .(1 -  r^10)/ (1 - r)
s10= 9. (1 - 1/3)^10 ) / (1 - 1/3)
s10 .= 3/2 (9) ( 1) = 27/2 = 13.5